It is well known that various elemental carbon materials can be employed as a pigment to provide conductivity in various applications. For example, U.S. Pat. No. 3,870,987, issued Mar. 11, 1975 to Wiley, et al., incorporated herein by reference, discloses a multi-layer ignition cable employing a graphite impregnated fiberglass conductor layer as well as a fluoroelastomer overcoating which employs graphite or conductive carbon black.
U.S. Pat. No. 3,868,313, issued to P. J. Gay, Feb. 25, 1975, discloses a cathodic protection system comprising applying an electrically insulating coating on the substrate followed by the application of an electrically conductive coating applied over the insulating coating. A D.C. voltage is then applied between the metal substrate and the conductive coating.
U.S. Pat. No. 3,151,050, issued Sept. 19, 1964, discloses methods for cathodic protection for vehicles and components in storage. The method comprises the application of an electrically conductive paint to the metal to be protected. The paint is a suspension of carbon, manganese dioxide, ammonium chloride and an organic filler and a solvent such as methyl-ethyl-ketone. A second coating of resin containing metallic copper is then applied, followed by a final coat of paint or enamel. Lastly a D.C. voltage is applied between the conducting paint and the metal base.
U.S. Pat. No. 4,035,265, issued July 12, 1977, to J. A. Saunders discloses electrically conductive paint compositions employing graphite and colloidal carbon. The graphite is subjected to wet grinding so as to reduce the graphite to thin platelets. The colloidal carbon employed consists of particles having a size from 20 to 50 millimicrons. The final composition (including the article it is applied to) is used as a heat source when electrical current is passed through the coating.
Other state-of-the-art efforts at carbon-containing coatings are found in
(1) U.S. Pat. No. 3,505,263, which discloses finely divided calcined petroleum coke in a polymer latex binder;
(2) U.S. Pat. No. 3,404,019, which discloses the use of fluid petroleum coke as a filler or pigment in polymeric compositions;
(3) U.S. Pat. No. 2,730,597, which discloses resistance elements which optionally employ various materials in a resin base;
(4) U.S. Pat. No. 4,476,265, which discloses poly (arylene sulfide) compositions which contain a "black carbonaceous pigment";
(5) U.S. Pat. No. 4,444,837, discloses coating or sealing-type plastisols which contain carbon dust as a filler;
(6) U.S. Pat. No. 3,391,103, which discloses phenolic resin compositions which employ "oxidized carbon particles";
(7) U.S. Pat. No. 3,615,754, which discloses an ink which employs 2 to 10 percent of ground coke; and
(8) U.S. Pat. No. 3,444,183, which discloses a film forming composition made from a heat-resistant polymer and a dispersion of carbon particles.